The present invention is directed to the replaceably engagement of drills in the drill socket of a hammer drill, or of a matcher or adaptor which in turn is replaceably mounted in a hammer drill.
Coupling means used for this or a similar purpose are shown in U.S. Pat. No. 3,690,390, German Published Examined Specification (DT-AS) No. 1,652,684, and German Published Unexamined Specification (DT-OS) No. 2,219,309.
In a hammer drilling device strong rotational and percussion forces are to be transmitted to a drill which is inserted in a socket of the hammer drill or of a matcher by which the drill is connected to the hammer drill comprising a source of rotational and percussion power. An essential feature of hammer drilling devices is that during rotation axial blows are transmitted to the drill. Therefore, either the drill in relation to the socket, or drill and socket together in relation to the source of percussion power must be able to reciprocate in axial direction over a limited interval, in reaction to the transmission impact. In consideration of the rather strong forces transmitted to the drill, and further by the latter to, e.g., a concrete wall, drills are coupled to the socket usually in that way that a special locking mechanism is provided, or that the engagement between the drill shaft and the socket is automatically tightened by the normal operation of the device so that substantial force is needed afterwards for removing the drill from the socket. For these reasons conventional hammer drills either make use of complicated and rather expensive sockets, or need quite a time for changing the tools.